From the Italian patent application No. 3376 A/87 and the corresponding copending U.S. application Ser. No. 07/154,782 filed concurrently herewith, an automatic machine is known for the continuous production of dual-use filter sachets for infusion products with bags or pouches in succession containing fractional doses of the infusion product.
The machine comprises along its production line succession of effecting successive steps in the production of such filter bags.
At the upstream end of the path there is a means for progressively folding and longitudinally sealing a strip of thermally weldable filter paper fed with the fractional doses of the infusion product into a horizontally oriented flattened tubular form and for thermally welding the tube transversely so as to enclose the individual fractional doses between two of the transverse thermal welds.
Downstream therefrom along the path is a further rotary wheel means with pickup elements for applying to the flattened tube equidistantially spaced labels as well as a continuous longitudinal thread transversely contacting the labels and stickers or tabls of thermally weldable material across the alternate transverse thermal welds partly to the back of the labels.
Further downstream is a means for cutting up the tube thus conformed into portions comprising at least two bags and for setting these up to back on each other and for sealing together their extremities.
More particularly, such a dual-use sachet of filter papers with multiple successive or serial bags or pouches, each containing a fractional dose or unit quantity of the infusion product, has a structure allowing two modes of use, namely one (nonconsumer made) in the flattened shape collated in lots for sale with the bags or pouches in a superimposed or adjacently set arrangement with one bag or pouch located or folded over the other, and one with an unfolded or extended arrangement of the pouches following pressing and pulling of the corresponding label located over the handling thread of the filter sachet by the user. The length of the thread is substantially equal to the length of the sachet in the unfolded arrangement of its bags or pouches and is fastened to the opposite extremity of the sachet by means of a sticker or tab made of thermally weldable material jointly with the label made of a not thermally weldable paper in proximity to one of these opposite extremities and is arranged to lie longitudinally along the outside of the sachet when the bags or pouches are in their collated arrangement in lots for sale, with the folded-back pouches backing against each other.